Implantable medical devices (IMDs) include, among other things, cardiac rhythm management (CRM) devices such as pacers, cardioverters, defibrillators, cardiac resynchronization therapy (CRT) devices, leadless pacing seeds, neuro-stimulators, as well as combination devices that provide more than one of these therapy modalities to a subject. Such implantable devices are typically powered by a battery. As the battery's useful life becomes exhausted, the implanted device may malfunction, causing errors in the therapy it provides, interfering with the operation of other IMDs, and/or its communication with other devices.